1. Field of the Invention
This invention relates to a digital beamforming array for use in radar applications and in particular in radar applications that use phased array technology.
2. Discussion of Prior Art
In many radar applications there is increasing evidence that the next generation or sensors will use active phased array technology. Such sensors comprise an array of modules, each having its own independent transmitter and receiver. Electronically steered transmit and receive beams can be generated by suitable phasing of the input and output signals or the modules. This enables rapid beam steering without moving mechanical parts, giving enhanced potential for multi-mode operation and/or low cost implementation.
An important extension of active array technology is the technique of digital beamforming. Here each module has a dedicated analogue to digital converter and the beamforming process is accomplished in the digital domain. This enables multiple receive beams to be implemented without the need for many bulky analogue beamforming manifolds. This ability to realise multiple receive beams is vital if monopulse or other precision target bearing determination schemes are to be implemented. Also the ability to sample the output or each module independently allows the implementation of adaptive beamforming and super-resolution algorithms, which are currently reaching a high degree or maturity. Furthermore, the algorithmic nature of the beamforming process means that it is possible for variations in the phase and amplitude responses of individual modules to be calibrated out by software means.
Balanced against these advantages of digital beamforming is the significant sensor cost penalty that can result from the requirement that each module has its own analogue to digital converter and the potentially high cost of the signal processing hardware required to implement the digital beamforming algorithm.